libsigc++: sigc::adapts< T_functor > Struct Template Reference

Base type for adaptors. More...

#include <sigc++/adaptors/adapts.h>

Inheritance diagram for sigc::adapts< T_functor >:

Public Member Functions

 adapts (const T_functor& functor)
 Constructs an adaptor that wraps the passed functor. More...


Public Attributes

adaptor_type functor_
 Adaptor that is invoked from operator()(). More...


Detailed Description

template<typename T_functor>

struct sigc::adapts< T_functor >

Base type for adaptors.

sigc::adapts wraps adaptors, functors, function pointers and class methods. It contains a single member functor which is always a sigc::adaptor_base. The adaptor_type alias defines the exact type that is used to store the adaptor, functor, function pointer or class method passed into the constructor. It differs from T_functor unless T_functor inherits from sigc::adaptor_base.

Example of a simple adaptor:
namespace my_ns
template <typename T_functor>
struct my_adaptor : public sigc::adapts<T_functor>
operator()() const;
template <typename T_arg1>
operator()(T_arg1 arg1) const;
template <typename T_arg1, typename T_arg2>
operator()(T_arg1 arg1, T_arg2 arg2) const;
// Constructs a my_adaptor object that wraps the passed functor.
// Initializes adapts<T_functor>::functor_, which is invoked from operator()().
explicit my_adaptor(const T_functor& functor)
: sigc::adapts<T_functor>(functor) {}
} // end namespace my_ns
// Specialization of sigc::visitor for my_adaptor.
namespace sigc
template <typename T_functor>
struct visitor<my_ns::my_adaptor<T_functor> >
template <typename T_action>
static void do_visit_each(const T_action& action,
const my_ns::my_adaptor<T_functor>& target)
sigc::visit_each(action, target.functor_);
} // end namespace sigc

If you implement your own adaptor, you must also provide your specialization of sigc::visitor<>::do_visit_each<>() that will forward the call to the functor(s) your adapter is wrapping. Otherwise, pointers stored within the functor won't be invalidated when a sigc::trackable object is destroyed and you can end up executing callbacks on destroyed objects.

Your specialization of sigc::visitor<> must be in namespace sigc.

Constructor & Destructor Documentation

template <typename T_functor>
sigc::adapts< T_functor >::adapts ( const T_functor &  functor)

Constructs an adaptor that wraps the passed functor.

functorFunctor to invoke from operator()().

Member Data Documentation

template <typename T_functor>
adaptor_type sigc::adapts< T_functor >::functor_

Adaptor that is invoked from operator()().